Stephenson, G.
Singpore: Longman, 1973
Buku Teks
Binmore, K.G., author
Cambridge University Press, 1995
Buku Teks
Adams, William J., author
Xerox College, 1975
Buku Teks
Narayan, Shanti
Shyam Lal Charitable Trust, 1982
Buku Teks
Bashirov, A. E., author
Elsevier, 2014
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